1. Field of the Invention
The present invention relates to a speech enhancement technology, particularly to a GSC-based spatially pre-processed TJR weighted filter and a method thereof.
2. Description of the Related Art
Speech interfaces using a two-microphone device has become popular in the consuming electronic products in recent years. There have been many research works involved in the two-channel speech enhancement issue, and one of the widely used schemes is the adaptive filter based on GSC (Generalized Sidelobe Canceller) structure. For two-microphone speech enhancement, the GSC structure allows one to pre-process the input signals by steering a beam and a null into the direction of a target source. It provides an efficient estimate of the characteristics of the target source and noise in a short time interval. The GSC structure is usually divided into three parts: a fixed beamformer, a blocking matrix (or vector), and a (multichannel) noise estimator.
The noise estimator uses the blocked signals and is commonly recommended to perform estimation in the absence of the target signal source lest the desired signal be cancelled. There are two common ways to start/stop estimation: one of them is to use a voice activity detector (VAD); the other one is to evaluate the auto- and cross-spectral densities from the inputs under a specified assumption. The former one relies on the performance of VAD, and the latter one might be impaired by a non-stationary coherent interference.
Accordingly, the present invention proposes a spatially pre-processed target-to-jammer ratio weighted filter and a method thereof to overcome the abovementioned problems. The principles and embodiments of the present invention will be described in detail below.